The present invention relates to a vehicle steering mechanism in which the axle bars can be locked at different distances from each other in order to adjust the track and in which the effective length of the tie rod connecting the axle bars can be changed correspondingly.
In many cases it would be advantageous and desirable for the track of a vehicle to be adjustable. It would be especially advantageous in farm tractors and garden tractors to adjust the track so that the wheels of the tractor would go into the furrows of a ploughed field or garden plot. In addition, it would be advantageous if the track could be adjusted to be maximal when driving on uneven terrain and, on the other hand, be reduced to minimal for the duration of transportation, for example when transporting a garden tractor on a trailer behind an automobile. In other respects it would also be advantageous if the track of a vehicle could be reduced temporarily, for example, when driving on narrow routes or when parking.
Numerous problems have been encountered so far in endeavors to create vehicle steering mechanisms with an adjustable track. When the distance between the axle bars has been changed in order to adjust the track, it has at the same time been necessary to adjust the length of the tie rod, in addition to which it has been necessary to readjust the steering angles. In order to produce a tie rod with an adjustable effective length, it has been necessary to make the tie rod from two parts which slide telescopically one inside the other and can be locked to each other. Such a structure is, however, relatively weak and easily bent by mechanical stresses and impacts it is subjected to.
Furthermore, the adjusting may be difficult to carry out, since the tie rod is exposed to soiling, and therefore the parts which slide one inside the other often stick to one another so that they become difficult or impossible to detach from each other. When a steering box is used, it is necessary to change the fastening point of the steering lever to the tie rod when adjusting the effective length of the tie rod. On the other hand, when worm and pin steering which acts directly on one axle bar is used, dead or nearly dead angles are easily produced if the track is spread too wide and the steering arm comes on the same straight line or nearly the same straight line as the axle of the wheel.
The previously proposed alternatives presented above also take up a great deal of space, they are complicated and function unreliably in practice. The object of the present invention is therefore to provide a vehicle steering mechanism in which the axle bars can be locked at different distances from each other in order to adjust the track and in which the effective length of the tie rod connecting the axle bars changes correspondingly without the steering angles having to be adjusted after the adjustment of the track. Furthermore, it is the object of the present invention to provide a vehicle steering mechanism which is. more reliable in operation, easier to operate, and structurally simpler than previous ones, and the main characteristics of the invention are given in the accompanying claims.